"Harry Krause" wrote in message
...
Out of curiosity, might someone who actually knows share how those "tire
pressure low" indicators work?

I don't mean the ones you put on your tire valves; I mean the ones that
come stock on some new vehicles, and set off a warning light on the dash
when a tire is low.

Oh, and I'm thinking of getting a set of valve pressure indicators for my
boat trailer tires. Any recommendations?

Thanks!

What I understand is they sense tire rpms and when all four aren't within
some tolerance the "Low Tire Pressure" warning is turned on.

I guess you could check this by putting equally low pressure in all four
tires and see if you get a warning.